Thermally marked target missile system

ABSTRACT

The missile system disclosed herein involves directing a beam from a  modeely powered laser on a taget for such time that a hot spot is produced. This hot spot is then used as a target for a cooperating infrared seeking missile.

BACKGROUND OF THE INVENTION

Previous missile systems for use against tanks and trucks required continuous guidance of the missile to the target or a heat seeking missile which homed in on the heat of the engine of the target vehicle.

It is an object of this invention to provide a missile system which does not require continuous operator guidance of the missile to the target, or continuous laser illumination.

A further object of the invention is to provide a missile system which employs a heat seeking missile which is effective against parked targets.

BRIEF DESCRIPTION OF THE DRAWING

The single FIGURE of the drawing is an artist's conception illustrating the missile system of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawing, the missile system of the present invention uses a laser 10 for thermally marking a target 12 creating a hot spot on the target. A heat seeking missile 14 launched from a launcher 16 then homes in on the hot spot thus created. The launcher may be located adjacent the laser or remote therefrom as illustrated.

The following table represents five different seekers contemplated for use in heat seeking missiles for the missile system described herein.

                                      TABLE I                                      __________________________________________________________________________                     Target Emission Power                                                          (normal to sensor)                                                 Threshold                                                                             Band (watts)     Background at 30° C.                        Sensor                                                                             (watts/cm.sup.2)                                                                      (microns)                                                                           1 km                                                                               2 km                                                                               3 km                                                                               (watts/cm.sup.2)                                   __________________________________________________________________________     1   6 × 10.sup.-11                                                                  3-5  1.885                                                                              7.55                                                                               17.0                                                                               7.5 × 10.sup.-4                              2   2 × 10.sup.-12                                                                  3-5   0.0628                                                                             0.251                                                                              0.565                                                                             7.5 × 10.sup.-4                              3   2 × 10.sup.-11                                                                   8-14                                                                               0.628                                                                              2.51                                                                               5.65                                                                               0.212                                              4   3 × 10.sup.-11                                                                  2.72-3.30                                                                           0.942                                                                              3.77                                                                               8.50                                                                               0.17 × 10.sup.-4                             5   4.5 × 10.sup.-11                                                                2.8-3.6                                                                             1.42                                                                               5.67                                                                               12.75                                                                              0.45 × 10.sup.-4                             __________________________________________________________________________

The laser power required for use with the several seekers depends further on the legnth of time the laser is turned on, the size of the spot illuminated, the time delay of acquisition and launch of the missile and the range to the target. The following charts show the laser power required for the several variables stated.

                  TABLE II                                                         ______________________________________                                         SENSOR #1                                                                      Spot  Beam                         Closure Speed                               Size  Time    Delay   Laser Power (kW)                                                                            V.sub.c at R.sub.o =                        r.sub.o                                                                              τ   τ.sub.d                                                                            at Range R.sub.o                                                                            1 km                                        (cm)  (sec)   (sec)   1 km 2 km  3 km  (m/sec)                                 ______________________________________                                         5     1       1        63  100   126   375                                                   5       120  200   250   125                                           3       1        26   42    57   125                                                   5        43   72    93   100                                           10      1        11   18    23    90                                     25    1       1       365  780   1130  250                                                   5       740  1440  1950   65                                           3       1       143  325   415   125                                                   5       230  470   650    60                                           10      1        70  130          60                                     50    3       1       260  690   1150  125                                                   5       450  1150  1850   50                                     ______________________________________                                    

                  TABLE III                                                        ______________________________________                                         SENSOR # 2                                                                     Spot  Beam                         Closure Speed                               Size  Time    Delay   Laser Power (kW)                                                                            V.sub.c at R.sub.o =                        r.sub.o                                                                              τ   τ.sub.d                                                                            at Range R.sub.o                                                                            1 km                                        (cm)  (sec)   (sec)   1 km 2 km  3 km  (m/sec)                                 ______________________________________                                         5     1       1       14.2 28    40    250                                                   5       27   54    70    85                                            3       1       6.3  12    17    125                                                   5       7.8  21    28    90                                            10      1       2.8    5.0   7.3 70                                      25    1       1       24   78    165   125                                                   5       36   144   310   40                                            3       1       11   33    73    60                                                    5       13   46    100   50                                            10      1       3.9    14.5                                                                               30    40                                      50    3       1            47    75    100                                                   5            66    130   45                                      ______________________________________                                    

                  TABLE IV                                                         ______________________________________                                         SENSOR # 3                                                                     Spot  Beam                         Closure Speed                               Size  Time    Delay   Laser Power (kW)                                                                            V.sub.c at R.sub.o =                        r.sub.o                                                                              τ   τ.sub.d                                                                            at Range R.sub.o                                                                            1 km                                        (cm)  (sec)   (sec)   1 km  2 km 3 km  (m/sec)                                 ______________________________________                                         5     1       1       15    44   82    40                                                    5       29    85   160   80                                            3       1         6.3 20   36    18                                                    5       11    32   58    60                                      25    1       1       20    67   157   80                                                    5       32    140  280   140                                           3       1        9    29   65    35                                                    5       13    54   100   50                                      ______________________________________                                    

                  TABLE V                                                          ______________________________________                                         SENSORS # 4 AND 5                                                              Spot  Beam                         Closure Speed                               Size  Time    Delay   Laser Power (kW)                                                                            V.sub.c at R.sub.o =                        r.sub.o                                                                              τ   τ.sub.d                                                                            at Range R.sub.o                                                                            1 km                                        (cm)  (sec)   (sec)   1 km 2 km  3 km  (m/sec)                                 ______________________________________                                         Sensor 4                                                                       5     3       1       36   50    66    300                                                   5       65   87    115   150                                     Sensor 5                                                                       5     3       1       37   52    65    300                                                   5       65   90    115   150                                     ______________________________________                                    

The above tables give figures representative of thick steel targets for various ranges up to 3 km and various times of exposure and spot sizes.

The following table gives similar figures for use of the system against relatively thin aluminum targets.

                  TABLE VI                                                         ______________________________________                                         Spot Size:    r.sub.o =                                                                             5 cm                                                      Thickness:    c =    0.3 cm                                                    Beam Time:    τ =                                                                               3 sec                                                     Delay:        τ.sub.d =                                                                         5 sec                                                     Convection:   h =    0.002 cal/cm.sup.2 sec °K.                         ______________________________________                                                Laser Power (kW)                                                               - a = ε = 0.2                                                                       - a = 0.5   ε = 0.7                                       Range        Range                                                      Sensor   1 km   2 km     3 km 1 km   2 km 3 km                                 ______________________________________                                         1        43     70       95   11.6   18   24                                   2        11     20       29   1.9    4.7  7                                    3        14     40       70   2      6    11                                   4        61     88       115  17.4   25.2 31.2                                 5        60     89       106  12.2   16.4 21.2                                        Plate Thickness: c = 0.2 cm                                             4        42     60       75   17.4   25.2 31.4                                 5        41     61       77   6.5    19.0 21.2                                 ______________________________________                                    

In general it can be seen from the above charts that a medium powered laser 50 kw to 150 kw with an average laser application time of approximately three seconds will create a hot spot suitale for use with most all of the different types of seekers at ranges up to 3 km. 

We claim:
 1. A missle system for intercepting a target including:a high power laser for heating said target for from 1 to 5 seconds to thermally mark said target by creating a hot spot thereon; and a heat seeking missile for intercepting said target by homing in on the heat radiating from said hot spot after said laser heating is removed.
 2. A missile system as set forth in claim 1 wherein said laser is between 50 kw and 150 kw in power.
 3. A missile system as set forth in claim 2 wherein the time for the seeker in said missile to lock onto said hot spot is from 1 to 5 seconds. 